TECH: Make a Bellhousing out of an old Intake Manifold!!

My goal here is to create the tech post I wish I had access to when I set out to start sand casting my own Hotrod parts. I did not know anyone who was doing their own casting, so I had to teach myself how to do it. The learning curve was very steep to say the least. Hopefully I can encourage some of you out there to take the leap and start casting your own parts. Using the Internet and every book I could get my hands on, I've been able to produce the following results straight out of my own garage. The aluminum I used came from old unwanted car parts such as transmission cases, intake manifolds and aluminum wheels:

















Hopefully I have your attention, because this tech post might a little get long and dry. I would guess that 90% of everything I needed to get started was already sitting in my garage. Everything else was readily available at the local pool supply, farmer's supply or home store.


Here is a basic list of what you will need. Some of these I'll show you how to make:

1. Melting Furnace (home-made)
2. Torch, to heat the furnace (home-made)
3. Crucible (home-made)
4. Dross-Skimmer (home-made)
5. Molding Sand (home-made)
6. Bentonite Clay in powder form (Sold as 'Pond Seal' at the farm store)
7. Flasks (for holding the sand mold, also home-made)
8. Sprue Cutter (home-made)
9. Baby Powder
10. Long Pants
11. Leather Boots
12. Long Sleeve Welding Jacket
13. Face Shield
14. Thick Leather Welding Gloves

 

Go cat go!!!

 

Great looking parts! Amazing talent!

 

Got my

1. Long Pants
2. Leather Boots
3. Long Sleeve Welding Jacket
4. Face Shield
5. Thick Leather Welding Gloves .......................On

 

Give me a minute... computer issues.

 

The Melting Furnace:


This is a picture of my 4 year old Furnace, and I have used it A LOT!




So that you can see how to build one yourself, I'm going to rebuild it, but even in it's dilapidated condition it still works great! I have melted using charcoal, used engine oil, fryer oil and propane with this very furnace. The furnace design is the same no matter what fuel you decide to use.


To make the Melting Furnace you will need:

a METAL 5 gallon bucket
a length of 2“ diameter exhaust pipe
an old steel wheel
some sheet metal

Take your metal bucket and cut a hole about 4“ from the bottom big enough for the exhaust pipe to fit through.



Leave about 5“ of the pipe sticking out on the outside and about 2“ on the inside. Weld the pipe to the bucket at a slight angle to the right as shown.







Now, you need to make an inner form for the furnace. I used a piece of card board rolled around a cylinder and taped it together like this:






Set the furnace body aside for now. Next is the furnace lid. I like to use a wheel because the wheel doesn't allow sand to come off of the bottom of the lid and get into the melt like other designs I've seen. Take the wheel and if necessary, enlarge the hole to about 3“ in diameter. Cut a strip of sheet metal and roll into a tube shape.Weld the tube closed and then weld it to the center opening in the wheel. Add to washers on each side of the wheel to attach the handle for the lid.







Now we need to make the refractory cement to coat the inside of the furnace. Refractory acts as insulation to keep the heat inside.


Refractory Cement:


When you make the refractory, the most important thing is to make sure you use clean silica sand. The grain size is not real important for the furnace, but when we make the molding sand, the grain size will come more into play. Silica sand will withstand very high temperatures without the grains exploding. In fact at very high temperatures the grains melt into glass. Not all sand is silica sand. If you are not sure if the sand you want to use will work, you can take a pinch of it on a metal plate and heat it with your torch (put your safety glasses on). If the sand just lays there and doesn't pop, you can most likely use it. You can get clean silica from your local pool supply. They use it in the pool filters. Here is a picture of the bag of sand I used when I made my furnace.




Next you need bentonite clay. You can get it at the local farmer's supply. Farmers use this stuff to line the bottom of ponds and troughs to keep the water from soaking into the ground. If you don't have a farmer's supply, I'm sure you could find someplace on the Internet where you can buy some. Here is a picture of the bag I used:



Dry mix the sand and clay at a 2:1 ratio (2 parts sand and 1 part clay). I like to use my wheelbarrow and garden hoe, but you could also use a large bucket and a stick or perhaps even a concrete mixer. Make sure you are wearing a respirator. Breathing silica dust will cause silicosis, and you can't make Hotrod parts if you're dead. Once it is dry mixed you need to 'temper' the mixture with water. It doesn't take much. Sprinkle the water a little at a time. Don't let the water pool or it will separate the ingredients. You want the mix to resemble stiff brick mortar.









The furnace continued:


I'm going to rebuild my furnace using real refractory mix. Lining your furnace with the homemade refractory mix is the same procedure.







You can get real refractory mix as well a many other casting supplies at www.budgetcastingsupply.com Take your bucket and layer 2” of the refractory mix into the bottom. Use a suitable tool to ram it tight.







Next take your cardboard form and place it in the middle. Now fill the rest of the space between the bucket and the cardboard a little at a time. Make sure to ram it solid, If you can't use something solid inside your form, be careful not to deform the shape of your cardboard tube.


















Strike off the top as shown and set it aside. Next take your lid form and pack refractory mix into the wheel as shown. Let the furnace sit overnight to cure slightly.

 

The next day remove the center cardboard form and clear the torch hole if needed.










Now your furnace is ready for heat curing. To heat cure, just insert your torch (made later in this thread), light it and put the lid on. Let it run for about an hour and then let it air cool. Any pieces that may fall out can be patched at anytime using the same mixture.



You need to have what is called a pilth. It is merely a stand for the crucible to set on. This allows heat to get at the bottom of the crucible. I use this piece of steel:











The torch:


I prefer to use a propane fired torch to heat my furnace. It's clean, it's easy and fast. As I mentioned earlier, I've heated using charcoal and used oil as well. Charcoal works well for small parts, and for a beginner, I'd say that charcoal a good way to get your feet wet. At the end of the thread I show you how to use charcoal. Used oil works real good too. You can melt cast iron with a used oil-fired torch. The drawbacks to used oil are the mess and storage of the oil. On the plus side, used oil is free.


I made my torch out of a weed burner, some pipe and fittings laying around the shop. The weed burner has a nice valve on the end to control the fuel flow rate.





I removed the bell off of the business end of the weed burner and installed an old fuel gauge so I can monitor the pressure. After the gauge, a length of brass pipe that goes into a piece of 1“ diameter pipe at a 90 degree angle. The 1” diameter pipe has 6, 3/8” vent holes and a bolt that holds the brass pipe in place. The key to the torch is the .030” orifice drilled 90 degrees into the brass pipe. The orifice faces down the torch.









When the fuel flows, it automatically mixes the air with the fuel. Then I put my vice grips on the end to act as a leg “so I can adjust the torch to my liking” (yeah right, I was just too lazy to make a leg for it!). Lastly, a metal spacer tack-welded onto the end of the 1” pipe to act as a flare while the torch is inside the furnace. It fits loosely inside the furnace's torch hole. I made mine out of an old bushing installer.


The Crucible:


The crucible is the pot that you melt the metal in. You don't have to have a real live one made from clay, graphite or silicon carbide. They are real pricey and fragile. I started using a stainless steel asparagus cooker. I attached 2 bolts to the top and a hook on the bottom. I then made a holder and a poorer stick to use with it. I don't use the steel one anymore. I do so much casting that I've upgraded to a real silicon carbide crucible. You can do just fine with a steel one. I didn't ever take a picture of my steel crucible set up, but I borrowed these 2 pictures from the net that show exactly what mine looked like:





The dross skimmer:


Dross is a layer of impurities that float to the top of your melt. Before you pour your molten metal into the sand mold, you remove the dross with a dross skimmer. Again, there is nothing earth shattering here, just a piece of rod with a scoop on the end. The holes help the molten metal out of the dross and back in the crucible.

 

there is a group called casting hobby group and it on yahoo.com

 

Molding sand:


The molding sand is where you are going to spend the most time with your home foundry. You are going to mix clean silica sand with bentonite clay. The idea is to coat each grain of sand with enough clay so that they will stick together when they are moistened. Use an 85 mesh or finer sand (the higher the number the finer the grains of sand). You will notice that the sand looks like fine granulated sugar. Add about 10% of clay by weight of sand. For example if you add 10lbs of clay to 100lbs of sand you will have roughly 10% clay by weight. You want enough clay to bond the sand together, but not so much that you clog up the porosity of the sand. The sand needs porosity to help vent the mold as it is poured. Dry mix your sand and clay (use a respirator). Then you are going to mix some type of flour into the mix. Corn, wheat what ever you have will work. Put about 2% flour in the mix. Now it's time To temper the mix with water. You are not going to use much. To add the water, don't just pour it in, sprinkle it on the mixture. It takes about 2 quarts of water for 100lbs of sand. Also, keep in mind it takes time for the clay to absorb the water. Give the sand about 30 minutes before you decide to add more water. Just enough water is added to be able to squeeze some sand into a sausage shape with your fist and have it hold together.











The other part of the “sausage test” is to break it in half







You want it to break clean, without crumbling up. DON'T ADD TOO MUCH WATER! Molding sand that is too wet will cause the pour to spit and sputter as it enters the mold. This is dangerous! The mold could even explode if it's real wet. So again, just enough water is added to temper the sand to pass the sausage test. Each time you use your molding sand you will have to test the bond using the sausage test. It's much less of a hassle to keep it in a sealed bucket when not in use. This keeps the sand closer to it's ideal temper.


Flasks:


Flasks are nothing more than boxes without tops or bottoms. They fit together with pins so that they align together perfectly. The top is called the “Cope” and the bottom is called the “Drag”.





All you have to do is take 8 pieces of equal length 2x4's and screw them together. Add some handles and some way for the two pieces to align when the mold is closed. Also adding a strip of wood to the inside will help hold the sand inside the flask.






I have all different sizes of flasks for different size projects. Make yours as big or as small as you want. You need to keep in mind that you will need room for the pattern, gates and sprue (all covered later). For what it's worth, here is a picture of my favorite flask



The sprue cutter:

After you have made your sand mold you need to provide a way for the metal to be poured in. This inlet passage, if you will, is called the Sprue. You make a sprue with a sprue cutter. It's just a rolled up piece of sheet metal in the shape of a cone. Welded together and ground smooth.

 

GO GO GO! This is what its all about. Love it

 

The sand mold:



I am going to show how to make a simple mold using this box cutter. First I coat the pattern with plenty of baby powder, and then blow the excess off.









Next take a flat board and spread a bit of baby powder across it so the sand won't stick to it. Place your pattern inside the flask:













Now “riddle” some sand over the pattern. I use a pasta strainer. You need about a ¼ inch of riddled sand over the pattern. The riddled sand contributes to the surface finish on the completed part. To fill the rest of the flask, riddled sand is not necessary. Add about 2 inches at a time and ram it tight with a suitable tool. Once the flash is full, strike the top flat.













Now we need to flip the flask over. Use another flat board to help flip it over.





Next the parting line is established. Use a suitable tool to carve down to where you want your parting line to be. Some patterns have very complicated parting lines. This pattern is simple.



Now sprinkle some “parting dust” (baby powder) on. Cover the entire area. The idea here is to spoil the bond between the to flasks.



Put the other half of the flask on and riddle some sand on the pattern. Fill with about 2 inches at a time and ram it up to the top. Strike off the top and then you are ready to open your mold.







Now take the end of your screwdriver and rap the pattern to loosen it. Remove the pattern.

 

I was lucky enough to go to a High School that still offered a foundry class. I really enjoyed it, Im still running some of the cast parts I made in there on my car. This is cool stuff!

 

Absolutely incredible post.

 

Now take your sprue cutter and cut a sprue. Next you cut the 'gates'. These are the paths from the sprue to the pattern cavity. I like to make a 'popper' at the end of my molds. It helps me to know when the mold is full of metal, because it fills up the popper. Here you can see the sprue, gates and popper getting cut.








Sometimes the top of the mold needs to be vented to let the air escape when it it filled. This is depending on the pattern. This mold didn't need it. If you do need to vent simply take a wire and poke it through in a few spots, that's all it takes.







Next, make a funnel shape to on the top of the sprue to help guide the metal into the mold. Blow away any loose sand and close the mold.



You are now ready to pour.



The melt:
It's best to premelt your material. This helps remove any impurities. I like to make cupcakes first, then Hotrod parts:

To help get your material into small enough pieces to fit inside the crucible, I like to use a sledge hammer. Some things such as wheels have to be heated before they will break apart. Just build a fire in your fire pit in the backyard and toss on the wheel. After about a half hour, the wheel will practically crumble when you hit it with the hammer.



Lighting the furnace and pouring:



Be safe. Wear everything you would when you are welding. Use a face shield too. This is one of those do as I say, not as I do moments; don't pour over concrete. If you loose hold of the crucible, if the mold pours out of the parting line or anything like that, the molten metal will cause the concrete to explode. Pour over bare dirt or lay down about 2” of sand in the area you will be pouring in. Plan your pour. Make sure you won't trip on anything and all of your tools are at hand.
Fill your crucible with material and place it inside the furnace. If you decide to use flux, put it in now. It isn't really necessary, but you can if you want to. Also degasser is available after the material is melted:




Put the lid on and insert the torch into the torch hole. Hold a match inside one of the vent holes in the torch and then turn the fuel on. It takes about 20psi of fuel pressure on my gauge for the furnace to run good. When the furnace heats up, you will notice a flame coming from the lid. You can add more material to the crucible through the exhaust port as it melts. Just use gloves and some long tongs, and don't put your head over the exhaust port!










I like to use a long poking rod to tell when the metal is molten. Just poke the melt, don't stir it. Stirring causes impurities to be mixed into the melt. After you can no longer feel solid pieces of metal in the crucible, I will let it heat for about 10 minutes more. A pyrometer would be real nice, but I haven't got one yet.
When you are ready to pour, turn off the fuel and remove the lid. Skim the dross off of the top and remove the crucible. Move it to the mold and pour. Keep the sprue choked. This means you are going to pour as fast as the mold will take the metal. Any left over material can be poured into a cupcake tray. Don't let it solidify in the crucible.















After you give the mold about an hour to cool, shake it out and see what you have. Here are the results from one of the above molds:

Obviously there is more to casting than I have covered here. This is just a basic run through. There is still multi layer flasks, sand cores and all kinds of other crazy stuff. Get your hands on some books or better yet someone who has done it. Let me warn you though, it's addicting. Soon you can't live without a mill or a lathe and it just snowballs from there. I can't look at a piece of speed equipment now without going through in my head how it was molded. Here are some books that I've read, read them. It's time well spent.




Patterns are a whole different subject, and I'm not going to cover much there. Basically you can use anything that will withstand being rammed in sand as a pattern. Here are a few shots of the patterns I've made. I like to use a base of steel in the basic shape and then use body filler for the rest:






I should add that a good place to get parts for your castings is www.mcmastercar.com

I would also recommend www.budgetcastingsupply.com

 

Is it Tech week already?. I'm off to the farm store.

 

Great post can't wait for more!

 

Charcoal firing:

If you want to play around with this before you get serious, charcoal is the way to go. Instead of a propane torch, you use a hairdryer and a length of flexable duct. Put one end of the duct tight over the torch hole in your furnace and put the hair dryer in the other. Now put 2 layers of charcoal in the bottom of your furnace. Add lighter fluid, light and wait till they are lit real good. insert your crucible and put some more charcoal between the crucible and the furnace sides. Put the lid on and start the hair dryer. Low speed works best. On high speed, you may get a larger flame from the vent hole, but most of your heat is being blown out of the furnace... That's it, nothing else to it.

 

Fantastic tech, reminds me of when I did it in a shop class 26 years ago at High School. I've always wanted to have a go again. Thanks for the inspiration

 

awsome job so far!

 

Cool been wondering how sand casting is or was done.

 

WOW! Nicely done!

 

an awesome thread i always found home casting to be fascinating there are some interesting casting sites on the internet one i liked had a nice tech thread on building your own furnace and different types of burners and their fuels

 

too cool.Something else I will have to try.

 

Great pics and info!

 

dave gingery rules! i did this in '92 everybody should try it !next time you see a part you will look at it in a whole new way! thanks for posting this well done!

 

This is very cool. Thanks for sharing.

 

This is what the HAMB is all about! Thanks...

 

same here, every once in a while I get thinking of my shop class and castings I did in 56-58

 

I don't want to complain as your thread is very informative with great pics, but how come no pics of the utility knife? The piece you showed with the sprues sticking off of it, what was that? How much gas does it take to fire enough material to cast a bellhousing, and would a pottery kiln work?

 

We did this in metals in 7<SUP>th</SUP> and 8<SUP>th</SUP> grade and iv always wanted to re try it. Thanks for showing.


1 safety question
Why are you pouring on concrete with sneekers on?